Mechanism for folding-in or folding-over the bottom



March 10, 1964 1-. JUNGMAYR 3,124,046

MECHANISM FOR FOLDING-IN OR FOLDING-OVER THE BOTTOM PARTS OF A BAG IN A BAG-FABRICATING MACHINE Filed Dec. 14, 1960 Arrylz United States Patent MECHANISM FGR FOLDING-IN 0R FOLDING- OVER THE BOTTGM PARTS OF A BAG IN A BAG- FABRICATING MACHINE Theodor Jungmayr, Stuttgart, Germany, assignor to Firms Fr. Hesser, Maschinenfahrik-Alttiengesellschaft, Stuttgart-Bad Cannstatt, Germany, a corporation of Germany Filed Dec. 14, 1960, Ser. No. 76,439 Claims priority, application Germany May 29, B56 2 Claims. (Cl. 93-12) The present invention relates to a mechanism which is particularly intended for use in bag-fabricating machines of the type which comprise a series of conveyor-supported folding mandrels. Each mandrel carries a bag tube which has been partially folded to leave two longitudinally projecting cars which are folded and creased by the mechanism of the invention to complete the closure of one end of the bag.

This application is a continuation-in-part of my copending application Serial No. 658,879 filed on May 13, 1957, and now abandoned.

In conventional apparatus for this purpose, folding slides are utilized which are carried by chains and which move along with the bag tubes at the same speed as the folding mandrels upon which the bag tubes are supported. Another conventional method for performing this folding operation is to provide stationary deflecting members which engage and flatten the projecting ears of each bag tube as it is conveyed past the deflecting members.

The provision of folding slides involves expensive and complicated machinery. The stationary deflectors, although inexpensive, produce an inferior product. This is primarily attributable to the fact that only the leading side edges of the projecting end flaps or cars engage the stationary folding deflectors so that the flaps are forced back by the movement of the conveyor mechanism, as a result of which not only are these end flaps rendered oblique with respect to the rectangular bottom of the bag, but in most instances they produce irregular bottom edges in the finished bag.

In accordance with the present invention, these disadvantages are avoided by the use, in a bag-fabricating machine, of a bottom-forming mechanism comprising at least one planetary gear arranged along the rectilinear path of travel of the folding mandrel and comprising a sun gear, a plurality of planet gears each having the same number of teeth as said sun gear and each individually rotatably mounted on a driven carrier, and a plurality of idler gears mounted on the carrier and each operatively connecting one of said planet gears to said sun gear, means for rotating said carrier at a rate corresponding to and .synchronized with the speed of travel of the folding mandrels, and a plurality of pivotally mounted folding fingers each connected for rotation by-one of the planet gears to main tain the pivotal axis of the folding finger parallel to the rectilinear path of'travelof the mandrels.

If, in accordance with a further feature of the invention, the carrier for the planetary gears, which carrier is advantageously shaped to form an enclosure for the gears, is synchronized with the speed of continuous travel of the folding mandrels, the individual folding slides, or fingers, not only travel a certain distance along with the folding mandrel, but at the same time carry out a movement at right angles to the direction of conveyance of the work by the mandrel, i.e. at right angles to the path of travel of the mandrel. This movement causes the folding finger to engage the projecting end flap of the bag tube. A cam-controlled pivotal movement is then imparted to the folding finger which causes it to move toward the end of the mandrel and to press the end flap toward the end 3,124,046 Patented Mar. 10, 1964 of the mandrel and against the previously partially folded end of the bag tube which is supported by the end of the mandrel. The folding action is followed by a transverse movement of the finger over the folded portion of the bag tube while holding the folded portion pressed together against the end of the mandrel. This transverse pressing movement creases the folded portion in a flattened condition so that properly finished folded edges are provided for the closed end of the completed bag.

Other objects and advantages of the invention are hereinafter set forth.

To facilitate understanding of the invention, a folding machine embodying the invention will now be described with reference to the accompanying drawing, in which:

FIGURE 1 is a front view of a folding mechanism according to the invention.

FIGURE 2 is a section on the line AA of FIG. 1.

FIGURE 3 is an end view of a modification of the invention, and

FIGURE 4 is a side view of a portion of FIG. 3.

The mechanism in the example illustrated is intended for the folding over and inwards of the tapered end flaps which are formed after a preceding folding inwards of two sides of the bottom section of a bag tube (not shown) projecting beyond a folding mandrel 1. Two planetary gear units designated generally as 2 and 3 respectively, are arranged above and below the rectilinear conveyor path F of the folding mandrel l, and these gear units are offset relatively to one another on the machine frame 4, with respect to the direction of travel of the mandrel, such that the preliminary and final working strokes for folding in the said end flaps will take place successively.

Each of the two gear units 2 and 3 comprises a fixed sun gear 5, three planet gears 7 rotatably mounted on a planet carrier 6 of plate form, and three intermediate idler gears 8 each individually in mesh with one of the planet gears 7 and with the sun gear 5. Each sun gear 5 is fast on a bearing sleeve 16 which is force fitted into one of the mounting posts -9 and 9', respectively, of gear units 3 and 2, and each planet carrier 6 is connected to a drive shaft 11 which is journaled in the sleeve 10. The planet carrier 6 is continuously driven by the shaft 11 at a rotary speed synchronized with the linear speed of travel of the series of bag supporting mandrels 1. The periphery of each planet carrier 6 is provided with a rim 12 so that each of these carriers forms a housing for the gears 5, 7 and 3 of one of the gear units 2 and 23.

The slides or fingers 13 for folding over the bottom end flaps are connected for rotation with the planet gears 7 and are so arranged that they can each be actuated through a limited pivotal movement about an axis which is always parallel to the rectilinear conveyor path P and perpendicular to the longitudinal axis of the mandrel 1. For this purpose each folding finger 13 is carried by a holder 15 which is mounted for pivotal movement on a support 14 carried by an extension of the shaft 7a on which the corresponding planet gear 7 in fast. Provided between each support 14 and the associated holder 15 are a compression spring 16 and aset screw 17 by means of which the normalor non-actuated position of the corresponding folding finger 13 may be adjusted.

To control the movement of the folding fingers 13, each of which must be at a predetermined initial distance from the end of the conveyor mandrel 1 at the beginning of the infolding operation and then progressively approach this end, use is made in connection with each gear of a fixed face cam 13.

The holder 15 of each folding finger 13 is provided at its free end with an anti-friction ball 19 which engages the face of the semi-circular cam 18 during the course of the folding operation. Each folding finger 13 is yieldingly urged toward the free end of the conveyor mandrel 1 by its associated compression spring 16 and is retracted by engagement of the ball 19 with the face of the semicircular cam 18. Each cam 18 is fixed to the machine frame either by a supporting bracket 29 associated with the lower gear unit 3 or by a supporting bracket 20 associated with the upper gear unit 2. Additional support is provided by a bearing 21 mounted in each cam 18. The free end portion of each drive shaft 11 is journaled in one of the bearings 21.

To bring about a parallel motion of the folding slides 13, the sun gear and the planet gears 7, which are in driving engagement with this sun gear through the intermediate idler gears 3, are provided with the same number of teeth.

In the embodiment presently described, a small relative displacement occurs between each folding finger and the corresponding mandrel in the direction of travel of the mandrel, the amount of this displacement being, however, of no significance to the method of folding here involved and referred to above. It arises from the fact that the folding finger moves through a circular arc and the mandrel along a straight line, as a result of which an exactly equal speed of the two parts occurs only at the apex of the arc.

If, however, the folding mechanism is to be used for other kinds of bottom-folding operation in which it is required that the folding finger shall have a velocity component in the direction of travel of mandrel 1 which is precisely equal to that of the mandrel 1 during one or more folding operations, the differences in the rectilinear speeds, which are quite slight per se, can be eliminated throughout the required equal speed interval by an auxiliary gear which is incorporated in advance of the planet gear. This auxiliary gear, FIGS. 3 and 4, can for example comprise an externally-and an internally-toothed spur gear arranged between which, as in an epicyclic gear, is an intermediate gear which is in mesh with the other two, this intermediate gear being in turn located on a web or arm which is mounted rotatably on the common axis of the spur gears. This web or arm is given a specific oscillatory motion by means of an eccentric, cam or crank drive, which alternately imparts a deceleration and an additional acceleration to the spur gear of the auxiliary gear which is connected to the driving shaft 11 and is driven by this intermediate gear, whereby the driving shaft 1-1 of the planetary gear 2 or 3 concerned is rotated with an approximately sinusoidal speed program. As a result, however, the rate of rotation of the folding slide, again related to the rectilinear direction, becomes uniform at every point in its operative path and can be set exactly to the rate of travel of the folder mandrel conveying the work.

The folding device according to the invention in the arrangement described, or a modified arrangement thereof, can, of course, be used directly for folding-in the top closure flaps of bag packages, if the closure of these packages is made by cross-folding or in similar fashion.

While I have shown what I believe to be the best embodiments of my invention, it will be apparent to those skilled in the art that various changes may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In a bag making machine, in combination: continuously operative conveyor means providing a rectilinear path of travel; a series of elongated regularly spaced mandrels carried by said conveyor means and extending outwardly therefrom with their longitudinal axes perpendicuiar to said path of travel, each of said mandrels having a flat free end adapted to have an incompletely folded end portion of a bag tube project therebeyond; two planetary gear means disposed adjacent to said path of travel at opposite sides thereof, each of said gear means being driven in synchronism with said conveyor means, the rotational axes of said gear means being parallel to said longitudinal axes, each of said gear means comprising a plurality of regularly arranged planet members which travel in a common circular path concentric with the rotation axis of its associated gear means, each of said planet members remaining substantially fixedly oriented with respect to said rectilinear path of travel during the course of its travel around said circular path, the rotational axis of one of said gear means being located beyond the rotational axis of the other gear means along said rectilinear path such that the common plane of the rotational axes of said two gear means is inclined obliquely with respect to said rectilinear path; a folding finger carried by each of said planet members; means mounting each folding finger on its respective planet member for pivotal movement about an axis perpendicular to the rotational axis of its associated gear means, each folding finger traveling in a circular path which intersects said rectilinear path with a free end portion of said finger progressively advancing and retreating laterally over said free end of one of said mandrels with a velocity component along the direction of travel of said mandrel which is substantially the same as that of the mandrel, the free end portions of successive fingers carried by each gear means passing over the free ends of successive mandrels; and cam means causing said free end portion of each finger to be displaced toward and away from said free end of said one of said mandrels during the course of said lateral advancing and retreating movement thereover, one of the fingers associated with one of said gear means preceding one of the fingers of said other of said gear means during the course of said lateral movements for performing two consecutive folding operations on said projecting end portion of each bag tube.

2. The combination according to claim 1, further comprising sinusoidally cyclically operative means connected to each of said gear means and driven in synchronism with said conveyor means, said sinusoidally operative means slightly displacing the orientation of said planet members for causing said velocity component along said direction of travel to be precisely equal to said velocity component of said mandrel.

References Cited in the file of this patent UNITED STATES PATENTS 1,843,027 Jahane Jan. 26, 1932 2,272,255 Vergobbi Feb. 10, 1942 2,691,329 Evers Oct. 12, 1954 

1. IN A BAG MAKING MACHINE, IN COMBINATION: CONTINUOUSLY OPERATIVE CONVEYOR MEANS PROVIDING A RECTILINEAR PATH OF TRAVEL; A SERIES OF ELONGATED REGULARLY SPACED MANDRELS CARRIED BY SAID CONVEYOR MEANS AND EXTENDING OUTWARDLY THEREFROM WITH THEIR LONGITUDINAL AXES PERPENDICULAR TO SAID PATH OF TRAVEL, EACH OF SAID MANDRELS HAVING A FLAT FREE END ADAPTED TO HAVE AN INCOMPLETELY FOLDED END PORTION OF A BAG TUBE PROJECT THEREBEYOND; TWO PLANETARY GEAR MEANS DISPOSED ADJACENT TO SAID PATH OF TRAVEL AT OPPOSITE SIDES THEREOF, EACH OF SAID GEAR MEANS BEING DRIVEN IN SYNCHRONISM WITH SAID CONVEYOR MEANS THE ROTATIONAL AXES OF SAID GEAR MEANS BEING PARALLEL TO SAID LONGITUDINAL AXES, EACH OF SAID GEAR MEANS COMPRISING A PLURALITY OF REGULARLY ARRANGED PLANET MEMBERS WHICH TRAVEL IN A COMMON CIRCULAR PATH CONCENTRIC WITH THE ROTATION AXIS OF ITS ASSOCIATED GEAR MEANS, EACH OF SAID PLANET MEMBERS REMAINING SUBSTANTIALLY FIXEDLY ORIENTED WITH RESPECT TO SAID RECTILINEAR PATH OF TRAVEL DURING THE COURSE OF ITS TRAVEL AROUND SAID CIRCULAR PATH, THE ROTATIONAL AXIS OF ONE OF SAID GEAR MEANS BEING LOCATED BEYOND THE ROTATIONAL AXIS OF THE OTHER GEAR MEANS ALONG SAID RECTILINEAR PATH SUCH THAT THE COMMON PLANE OF THE ROTATIONAL AXES OF SAID TWO GEAR MEANS IS INCLINED OBLIQUELY WITH RESPECT TO SAID RECTILINEAR PATH; A FOLDING FINGER CARRIED BY EACH OF SAID PLANET MEMBERS; MEANS MOUNTING EACH FOLDING FINGER ON ITS RESPECTIVE PLANET MEMBER FOR PIVOTAL MOVEMENT ABOUT AN AXIS PERPENDICULAR TO THE ROTATIONAL AXIS OF ITS ASSOCIATED GEAR MEANS, EACH FOLDING FINGER TRAVELING IN A CIRCULAR PATH WHICH INTERSECTS SAID RECTILINEAR PATH WITH A FREE END PORTION OF SAID FINGER PROGRESSIVELY ADVANCING AND RETREATING LATERALLY OVER SAID FREE END OF ONE OF SAID MANDRELS WITH A VELOCITY COMPONENT ALONG THE DIRECTION OF TRAVEL OF SAID MANDREL WHICH IS SUBSTANTIALLY THE SAME AS THAT OF THE MANDREL, THE FREE END PORTIONS OF SUCCESSIVE FINGERS CARRIED BY EACH GEAR MEANS PASSING OVER THE FREE ENDS OF SUCCESSIVE MANDRELS; AND CAM MEANS CAUSING SAID FREE END PORTION OF EACH FINGER TO BE DISPLACED TOWARD AND AWAY FROM SAID FREE END OF SAID ONE OF SAID MANDRELS DURING THE COURSE OF SAID LATERAL ADVANCING AND RETREATING MOVEMENT THEREOVER, ONE OF THE FINGERS ASSOCIATED WITH ONE OF SAID GEAR MEANS PRECEDING ONE OF THE FINGERS OF SAID OTHER OF SAID GEAR MEANS DURING THE COURSE OF SAID LATERAL MOVEMENTS FOR PERFORMING TWO CONSECUTIVE FOLDING OPERATIONS ON SAID PROJECTING END PORTION OF EACH BAG TUBE. 